The specificity of the endo-N-acetylglucosaminidase isolated from S. grisens, as well as two commercially available enzymes recently announced by Miles Laboratories, toward the glycopeptide of RBP and native RBP will be investigated with the dual goals of: (1) isolating the nearly intact oligosaccharide from the glycopeptide for further structural studies and (2) recovering deglycosylated RBP for continued investigations of the function of CHO portion of glycoproteins. Efficiency of transfer of labeled deglycosylated to the yolk of laying hens offers a very good model for such studies. CHO appears to play no role in vitamin binding efficiency. Attempts to show regions of homology between RBP, Pro-RBP and altered RBP (CRM) will be continued with the micro-ion exchange methods using fluoropa detection. Solubilization of peptides derived from tryptic digests of succinylated RBP has presented problems which are being solved by regulation of the pH of the eluting buffers. Livers of the Rdrd genotype will be examined to show the existence of Pro-RBP and altered RBP (CRM). CRM does not inhibit RBP antibody reaction. On the other hand, both proteins show identity on Ouchterlony assay. The results of these studies with the RdRd gene will be utilized to explore the nature of altered AVT function in didi mutants and the role of CaBP of serum in relation to shell quality for thick- and thin-shell lines.